National has ruled out repealing the Zero Carbon Act, and poured cold water on ACT's proposal to redefine Treaty of Waitangi principles.
However, leader Christopher Luxon has stopped short of ruling out the ACT's Treaty policy.
Last night's 1News-Verian poll had support for both National and ACT up, giving the right bloc the numbers to comfortably form the next government with 65 seats between them.
Senior Labour MP Kelvin Davis said there was a lot at stake if his party did not win the election, adding he had a particular concern for Māori under a National-ACT government arrangement.
"One of the big things is that ACT wants to redefine the principles of Te Tiriti o Waitangi. Māori have always been firm and adamant about rangatiratanga as important to them and there's no place for rangatiratanga under a National-ACT government - and that's a real fear."
ACT staunchly opposes co-governance and wants to change the country's constitutional settings.
It wants to do this by passing a Treaty Principles Act that would supercede the Treaty of Waitangi and its implications in other legislation and the way laws are interpreted in court.
Labour's Willie Jackson said ACT's leader David Seymour was "going down the same way as Trump" by trying to overturn principles entrenched by New Zealand's top legal experts and successive Labour and National prime ministers.
"Luxon needs to rule him [Seymour] out. If Luxon wants to agree with Seymour he would be walking on the mana of Jim Bolger, of Doug Graham, of John Key and of Bill English.
"All of these prime ministers never had a problem with what Seymour's got a problem with. Seymour's not an expert on this; he's not a top lawyer, he's not a top judge. Every judge since 1987 has supported what this government is doing and what the previous National governments were doing."
National's leader Christopher Luxon was initially reluctant to comment on ACT's proposal to redefine the Treaty principles, saying it was a conversation that would happen in post-election negotiations, not through the media.
"I'm not going to get into any of those conversations because that will happen as part of coalition negotiations when we think about that, but that is not our policy, it is not a National Party policy."
Asked if National was aligned with ACT's approach to Treaty issues, Luxon said his party did not support co-governance in public services but did not have a policy of redefining the Treaty of Waitangi.
"I'm saying to you that [redefining treaty principles] is something that's not our policy and we don't support it."
Luxon was definitive when asked if his party supported ACT's policy to repeal the country's legislative framework to curb emissions, the Zero Carbon ACT.
"Absolutely not. We believe very strongly in net-zero 2050. The means by which we deliver those goals will be different from the government but we are deeply, deeply committed to that."
ACT leader David Seymour said the only thing he would say to Luxon was that the country had not yet had an election.
"The power's with the voters. Now they can see if they want real change on these important issues they've got to give their party vote to ACT."
Davis remained sceptical about National's approach to race relations, saying Luxon should definitively rule out redefining the Treaty.
"I think that National needs to clarify where they stand because at the moment under a National-led government - I think that the tail will wag the dog, and National haven't been clear on where they stand on kaupapa Māori."
Senior Labour MP Andrew Little, who holds the Treaty of Waitangi Negotiations portfolio, said even though ACT had supported Treaty settlements it had not participated in deed-signing ceremonies on marae where kōrero about anguish and healing took place.
"I think they're ignorant of New Zealand's history and there's a part of the history that they don't want to recognise. It's the sort of history that we do want to teach New Zealanders because it has been hidden too long.
"It is the history of the pain and hurt caused by the breaches of the Treaty. It's a history that has prospects for a quite different outcome in the years ahead - but we have to own the past in order to get to the future, and they don't want to be part of that."
The National Party has also responded to New Zealand First's policy to pass legislation banning trans women from women's bathrooms.
Asked if her party would rule this out now, National's deputy leader Nicola Willis said that was not what National was focused on.
"Our focus is on the cost of living crisis and rising violent crime ... we haven't even discussed the prospect ... it's not something we've even had on the table."